Problem Library

Master these coding challenges to ace your next technical interview. Handpicked problems with personalized spaced repetition.

All tracks Blind 75 NeetCode 150 NeetCode 250 Striver A to Z SDE Sheet

Showing 51-75 of 75 matching problems in Blind 75.

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All topics Array Backtracking Binary Lifting Binary Search Binary Search Tree Binary Tree Bit Manipulation Bracket Sequences Breadth-First Search Brute-Force Search Bucket Sort Combinatorics Complete Knapsack Counting Data Stream Depth-First Search Design Directed Acyclic Graph

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Array36String19Depth-First Search18

These are the topics showing up most often in your current queue.

Title	Difficulty	Topics
226. Invert Binary Tree Open source	Easy	TreeDepth-First SearchBreadth-First Search+1 more
230. Kth Smallest Element in a BST Open source	Medium	TreeDepth-First SearchBinary Search Tree+1 more
235. Lowest Common Ancestor of a Binary Search Tree Open source	Medium	TreeDepth-First SearchBinary Search Tree+3 more
238. Product of Array Except Self Open source	Medium	ArrayPrefix Sum
242. Valid Anagram Open source	Easy	Hash TableStringSorting
252. Meeting Rooms Open sourcePremium	Easy	ArraySortingQuicksort
253. Meeting Rooms II Open sourcePremium	Medium	ArrayTwo PointersGreedy+3 more
261. Graph Valid Tree Open sourcePremium	Medium	Depth-First SearchBreadth-First SearchUnion-Find+1 more
268. Missing Number Open source	Easy	ArrayHash TableMath+3 more
269. Alien Dictionary Open sourcePremium	Hard	ArrayStringDepth-First Search+4 more
271. Encode and Decode Strings Open sourcePremium	Medium	ArrayStringDesign
295. Find Median from Data Stream Open source	Hard	Two PointersDesignSorting+2 more
297. Serialize and Deserialize Binary Tree Open source	Hard	StringTreeDepth-First Search+3 more
300. Longest Increasing Subsequence Open source	Medium	ArrayBinary SearchDynamic Programming+1 more
322. Coin Change Open source	Medium	ArrayDynamic ProgrammingBreadth-First Search+2 more
323. Number of Connected Components in an Undirected Graph Open sourcePremium	Medium	Depth-First SearchBreadth-First SearchUnion-Find+1 more
338. Counting Bits Open source	Easy	Dynamic ProgrammingBit Manipulation
347. Top K Frequent Elements Open source	Medium	ArrayHash TableDivide and Conquer+5 more
371. Sum of Two Integers Open source	Medium	MathBit Manipulation
417. Pacific Atlantic Water Flow Open source	Medium	ArrayDepth-First SearchBreadth-First Search+1 more
424. Longest Repeating Character Replacement Open source	Medium	Hash TableStringSliding Window
435. Non-overlapping Intervals Open source	Medium	ArrayDynamic ProgrammingGreedy+1 more
572. Subtree of Another Tree Open source	Easy	TreeDepth-First SearchString Matching+2 more
647. Palindromic Substrings Open source	Medium	Two PointersStringDynamic Programming
1143. Longest Common Subsequence Open source	Medium	StringDynamic ProgrammingLongest Common Subsequence